The Bob 3-4 or Neil Vein occurrence is centred on the Bob 3 and 4 claims, 6.5 kilometres south of Yedhe Creek, 10 kilometres east of Toad River, in the Muskwa Ranges in the Northern Rocky Mountains approximately 166 kilometres west of Fort Nelson (Assessment Report 3420, Map 14).
The occurrence is in a region known as the Muskwa Anticlinorium, a major north-northwest trending structure characterized by moderate folding and thrust faulting. The structure consists of Middle Proterozoic (Helikian) rocks of the Muskwa Assemblage, as well as Paleozoic rocks (Geological Survey of Canada Map 1343A; Geological Society of America, Geology of North America, Volume G-2, pages 111, 639). All belong to Ancestral North America (Geological Survey of Canada Map 1713A). Northeast to northwest trending diabase dikes of Proterozoic age are common in the region.
The showing area is underlain mainly by the Aida Formation of the Muskwa Assemblage (Geology, Exploration and Mining in British Columbia 1971; Geological Survey of Canada Memoir 373). In this area, this unit comprises calcareous and dolomitic mudstone and slate, silty mudstone, dolostone, limestone and minor quartzite (Assessment Report 3420; Property File - Adamson, R.S., 1971). Bedding strikes northwest and dips moderately southwest. Locally the rocks are folded, sheared and faulted, and are intruded by several northeast striking diabase dikes.
A prominent shear zone passes through the area, striking about 045 degrees. It is approximately 30 metres wide and has been traced for 1.1 kilometres horizontally, and 425 metres vertically. Coincident with the shear zone is a large diabase dike, forming a resistant spur. It dips steeply and is between 2 and 12 metres thick. Its contacts are sheared and altered, as is the adjacent slaty mudstone wallrock. The dike and the shear zone are important as they host a discontinuous series of mineralized quartz-carbonate veins, occurring at or close to the dike's contacts in the shear zone. The constituent veins have the same general orientation, but may vary in attitude on a smaller scale. The veins range in thickness from a few centimetres to 2.75 metres; most are under 1 metre thick. They may have originally been a single vein, known as the Neil vein, which has been disrupted by shearing into smaller lenses. The age relationship between the dike's intrusion and the veining is uncertain; at least some shearing post-dates both.
The veins are composed of quartz and ankerite, and may have inclusions of wallrock. Chalcopyrite is sporadic and occurs in variable amounts, along with very minor bornite and pyrite. Secondary malachite and azurite are common. Very locally, there are small blebs and stringers of galena.
This occurrence is centred on veins at the eastern end of the exposed dike, on a small topographic peak at the common corner of the Bob 3 and 4 claims (Assessment Report 3420, Map 14). A related occurrence, the Ann 18 prospect (094K 057), is towards the western end. This area is also the site of a major breccia zone, developed between a thick bedded dolostone subunit and the shear zone. The zone comprises angular fragments of black dolostone in a stockwork of quartz and brown carbonate. It is at least 215 metres long and 7.5 metres wide, and strikes 080 degrees, somewhat oblique to the shear zone. Chalcopyrite is disseminated in the quartz. The best chip sample from this area came from Trench 2 in the breccia zone, assaying 3.67 per cent copper over 0.9 metre (Assessment Report 3420). The average copper content was 2.4 per cent across 1.8 metres, in oxidized rock (Assessment Report 3420). A chip sample in unaltered material assayed 4.8 per cent copper over 7 metres (Assessment Report 3420, page 2; Property File - Adamson, R.S., 1971).
Exploration in the area dates back to the early 1960s when copper-bearing quartz-carbonate vein showings were discovered in the Muskwa Anticlinorium. Two of them, Neil Vein (094K 040, this description) and Ann 18 (094K 057, also referred to as the Neil Vein) lie within the Neil property of A.R. Raven (ca. 2016). These two occurrences are at the northeast and southwest ends, respectively, of what is believed to the same mineralized vein structure. The veins are referred to by different names. The Neil Vein (094K 040) is also referred to as the Bob 3-4, Ram Creek and Okey Vein, and the Ann 18 Vein (094K 057) has also been referred to as the Neil Vein.
In 1971, Alberta Copper undertook an exploration program of geological mapping and trenching on the Neil Vein covered by the Bob claims which comprised their Ram Creek Property.
Renewed interest in the property was shown in 1992 (George Cross News Letter, Number 87, May 5).
In 1996, a program on behalf of Seguro Projects Inc. consisted of prospecting and sampling the Neil Vein and associated breccia zone; 10 samples were collected and analyzed.
In 1997, Seguro Projects Inc. undertook geochemical sampling of the Neil Vein which then was included in their Okey property. Fifty-six chip samples of vein and breccia were collected and analyzed.
In 2002, Senator Minerals Inc. held an option on the property from Seguro and carried out a work program designed to locate, sample and determine the extent of the brecciated dolomite (the ‘breccia zone’) at the northeastern extremity of the Neil Vein, and to locate and sample the Neil Vein. Two chip and three select rock samples were collected from the area of the Neil Vein and one select sample was taken from brecciated dolomite float. Copper values from Neil Vein samples ranged from 11 to 2460 parts per million (ppm). The sample of brecciated dolomite float yielded 21 ppm copper.
In 2003, Seguro Projects undertook additional rock chip sampling from six locations proximal to the north ridge zone and about 130 metres to the northeast along the Neil Vein.
In 2005, Seguro optioned the claims that covered the Neil Vein to Action Minerals Inc. At this time some interest in the property was also held by Aries Resource Corp. In that year, Action Minerals undertook very limited rock sampling in the breccia zone at the northeast end of the Neil Vein. The coordinates are believed to be in the NAD27 datum but when converted to NAD83 datum they do not correspond well to the mapped location of the Neil Vein (Assessment Report 36327).
A high level magnetometer survey of the area was flown by Sanders Geophysics Ltd. in 2005 for Archer Cathro Associates and acquired by Action and Aries who then contracted McPhar Geosurveys Ltd. and Aeroquest Surveys in 2006 to acquire aeromagnetic and electromagnetic (EM) coverage over their project area which included the Neil property. Interpretations from this data suggest that the mineralized veins in the area parallel the dike trends and that quartz-carbonate veins are nearly always associated with the dike systems.
In 2011-12, a program included limited rock sampling, a summary of the airborne magnetic and EM results and an investigation of iron oxide and hydroxyl alterations using ASTER imagery.
In 2016, a geological remote sensing and structural study was undertaken for A.R. Raven. The study utilized digital elevation models (DEM’s), Landsat 7 ETM, ASTER and WorldView2 satellite imagery and was, in part, follow-up work to satellite imagery analysis performed in 2012. The objectives of the study were to provide information on the structural geology and prepare image and base maps suitable for future field work.